1. Field of the Invention
The present invention relates to a method of synthesizing new improved proteins from a methanol containing culture, by means of methylotrophic microorganisms selected as glycine resistant mutants.
2. Description of the Prior Art
Numerous attempts have been made in the prior art to prepare methylotrophic microorganisms using methanol by way of serine (2-amino-3-hydroxypropionic acid). Those microorganisms which have been isolated by the conventional methods such as repeated picking out of the microorganisms from a medium using methanol as the sole source of carbon, have kinetic performances which are frequently mediocre.
In methods of producing proteins from unicellular organisms, the strain of microorganisms is of considerable importance. For a given carbon substrate, the biological values of the product, such as absence of toxicity, the degree of nutritional value, or the like, depend upon the particular strain. Also, the economics of continuous industrial production of the proteins are highly dependent upon the particular strain so it is important that the selection be performed with certainty and care. A most important value of a particular strain would appear to be the kinetic performances of the strain which dictates the extent of the scale of the industrial installation and, hence, the capital investment required.
Although the methods of isolating strains by continuous selection make it possible to isolate the performing strains, these methods are, nevertheless, protracted since it takes at least one month of experimentation in a continuous fermenter. The methods are delicate and the results hazardous. On the other hand, only an enrichment of microorganism is achieved in this way and it is essential to isolate the best performing microorganism from the complex flora being processed.
Some of the prior art attempts are described in the literature, more particularly, in the following texts: W. Harder, M. M. Atwood, J. R. Quayle, J. Gen. Microbiol. (1973) 78 155-163, Asthana et Coll. Biotechnol, Bioeng. (1971) 13, 923 and (1971) 8, 923, M. Reuss et Coll. Eur. J. Appl. Microbiol. (1975) 1, 295-305, Whittenbury et al. J. Gen. Microbiol. (1970), 61 205, Hirsh and Conti Archiv. Fin Mikrobiologie (1964) 43; 358, Ogata et Coll. J. Ferment. Technol. (1970) 48, 470.
Applicants have discovered that, among the strains which metabolize methanol by way of serine, the resistance to glycine habitually involves an increased utilization of methanol.
It has now been found that, by practice of the present invention proteins may be prepared from methanol with improved strains which are characterized as glycine-resistant methylotrophic strains.